Semiconductor device and method for manufacturing semiconductor device

Abstract

According to one embodiment, a semiconductor device includes a first electrode, a second electrode, a first region, a second region, a third region, a first conductive portion, a second conductive portion, a gate electrode, a first insulating portion, a second insulating portion, a third insulating portion, and a fourth insulating portion. The second electrode has a first portion and a second portion extending from the first portion toward the first electrode. The first region is between the first electrode and the second electrode. The second region is between the first region and the second electrode. The third region is between the second semiconductor region and the second electrode. The first conductive portion is in the first semiconductor region. The gate electrode is between the second region and the second portion. The second conductive portion is between the first conductive portion and the gate electrode.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a first electrode;   a second electrode spaced from the first electrode in a first direction;   a first semiconductor region of a first conductivity type between the first electrode and the second electrode and electrically connected to the first electrode;   a plurality of second semiconductor regions of a second conductivity type between the first semiconductor region and the second electrode and spaced from one another in a second direction intersecting the first direction;   a third semiconductor region of the first conductivity type electrically connected to the second electrode and between the second semiconductor regions and the second electrode in the first direction;   a first conductive portion adjacent to the first semiconductor region in the second direction;   a first insulating portion between the first conductive portion and the first semiconductor region in the second direction;   a gate electrode between adjacent pairs of the second semiconductor regions in the second direction;   a second conductive portion between the first conductive portion and the gate electrode in the first direction;   a second insulating portion between the first conductive portion and the second conductive portion in the first direction;   a third insulating portion between the gate electrode and adjacent second semiconductor regions in the second direction and the first semiconductor region and the second conductive portion in the second direction; and   a fourth insulating portion between the gate electrode and the second conductive portion in the first direction, wherein   the second electrode has a first portion spaced from the third semiconductor region in the first direction and a second portion that extends from the first portion in the first direction and contacts the second conductive portion.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein the second conductive portion is adjacent to the gate electrode in the first direction via the fourth insulating portion. 
     
     
         3 . The semiconductor device according to  claim 2 , wherein a distance from the second conductive portion to the first semiconductor region along the second direction is less than a distance from the gate electrode to the first semiconductor region along the second direction. 
     
     
         4 . The semiconductor device according to  claim 1 , wherein
 the gate electrode between the adjacent pairs of the second semiconductor regions has a first part closer to a first one the pair of second semiconductor regions in the second direction and a second part closer to a second one the pair of second semiconductor regions, and   the second portion of the second electrode is between the first and second parts of the gate electrode in the second direction.   
     
     
         5 . The semiconductor device according to  claim 4 , wherein the second conductive portion is adjacent to the first and second parts of gate electrode in the first direction via the fourth insulating portion. 
     
     
         6 . The semiconductor device according to  claim 1 , wherein the second electrode includes a third portion extending from the first portion in the first direction, the third portion being electrically connected to the second and third semiconductor regions. 
     
     
         7 . The semiconductor device according to  claim 1 , wherein the second conductive portion comprises polysilicon. 
     
     
         8 . The semiconductor device according to  claim 1 , wherein
 the first conductivity type is n-type, and   the second conductivity type is p-type.   
     
     
         9 . The semiconductor device according to  claim 1 , wherein the first conductive portion and the second conductive portion are electrically connected to the second electrode. 
     
     
         10 . A semiconductor device, comprising:
 a semiconductor layer;   a first electrode on a first side of the semiconductor layer;   a second electrode on a second side of the semiconductor layer;   a plurality of trenches extending into the semiconductor layer in a first direction from the second side of the semiconductor layer and spaced from one another in a second direction intersecting the first direction, wherein   the second electrode includes:
 a first portion separated from the semiconductor layer in the first direction, 
 a second portion extending in the first direction from the first portion into the plurality of trenches, and 
 a third portion extending in the first direction from the first portion into the semiconductor layer between adjacent trenches in the second direction, 
   the semiconductor layer includes:
 a first semiconductor region of a first conductivity type between the first electrode and the second electrode and electrically connected to the first electrode, 
 a plurality of second semiconductor regions of a second conductivity type between the first semiconductor region and the second electrode and spaced from one another in the second direction, and 
 a third semiconductor region of the first conductivity type electrically connected to the second electrode and between the second semiconductor regions and the second electrode in the first direction, and 
   each trench has therein:
 an insulating material, 
 a first conductive portion adjacent to the first semiconductor region in the second direction, a first insulating portion of the insulating material being between the first conductive portion and the first semiconductor region in the second direction, 
 a gate electrode between adjacent pairs of the second semiconductor regions in the second direction, and 
 a second conductive portion between the first conductive portion and the gate electrode in the first direction, a second insulating portion of the insulating material being between the first conductive portion and the second conductive portion in the first direction, 
   a third insulating portion of the insulating material is between the gate electrode and adjacent second semiconductor regions in the second direction and the first semiconductor region and the second conductive portion in the second direction, and   a fourth insulating portion of the insulating material is between the gate electrode and the second conductive portion in the first direction.   
     
     
         11 . The semiconductor device according to  claim 10 , wherein the first conductive portion and the second conductive portion are electrically connected to the second electrode. 
     
     
         12 . The semiconductor device according to  claim 10 , wherein the second conductive portion is below the gate electrode in the first direction. 
     
     
         13 . The semiconductor device according to  claim 10 , wherein the second conductive portion comprises polysilicon. 
     
     
         14 . The semiconductor device according to  claim 10 , wherein the gate electrode in each trench has a first part closer to a first one the adjacent second semiconductor regions in the second direction and a second part closer to a second one of the adjacent second semiconductor regions in the second direction, and the second portion of the second electrode is between the first and second parts of the gate electrode in the second direction. 
     
     
         15 . The semiconductor device according to  claim 10 , wherein a distance from the second conductive portion to the first semiconductor region along the second direction is less than a distance from the gate electrode to the first semiconductor region along the second direction. 
     
     
         16 . The semiconductor device according to  claim 10 , wherein the semiconductor layer is silicon. 
     
     
         17 . A method of manufacturing a semiconductor device, the method comprising:
 forming a trench in a first semiconductor region of a first conductivity type, the trench extending in a first direction into the first semiconductor region from a first side;   forming a first insulating portion on the first side and an inner wall surface of the trench;   forming a first conductive portion in the trench on the first insulating portion;   removing an upper portion of the first conductive portion and then forming a second insulating portion in the trench on a remaining lower portion of the first conductive portion;   removing a part of the first insulating portion and a part of the second insulating portion from the trench to expose an upper part of the inner wall surface;   forming a second conductive portion in the trench on an upper surface of a remaining part of the first and second insulating portions;   oxidizing a part of the second conductive portion to form a third insulating portion on the upper part of the inner wall surface of the trench and a fourth insulating portion on an upper surface of the second conductive portion;   forming a gate electrode in the trench on a surface of the third insulating portion and a part of the fourth insulating portion;   forming a second semiconductor region of a second conductivity type in the first semiconductor region, the second semiconductor region being adjacent to the gate electrode via the third insulating portion in the second direction; and   forming a third semiconductor region of the first conductivity type above the second semiconductor region in the first direction.   
     
     
         18 . The method according to  claim 17 , wherein the second conductive portion is polysilicon. 
     
     
         19 . The method according to  claim 17 , further comprising:
 forming a first electrode on a second side of the first semiconductor region.   
     
     
         20 . The method according to  claim 19 , the method further comprising:
 forming a second electrode on the first side of the first semiconductor region, the second electrode including a portion extending in the first direction into the trench and contacting the second conductive portion, and another portion extending in the first direction into the second semiconductor region.